Field of the Invention
The present disclosure relates to an electrophotographic photosensitive member, a process cartridge, an electrophotographic apparatus, a charge transport layer forming coating liquid, and a method for manufacturing the electrophotographic photosensitive member.
Description of the Related Art
Electrophotographic apparatus users have recently been being diversified. It is desirable that the electrophotographic apparatus can output more high-quality images than ever without varying image quality over the period of use. Accordingly, it is also desirable that the electrophotographic photosensitive member incorporated in such an electrophotographic apparatus respond to these demands.
For forming high-quality images over a long time from the beginning, Japanese Patent Laid-Open No. 2013-142705 discloses an electrophotographic photosensitive member including a photosensitive layer having a surface layer containing 100 ppm by mass to 2500 ppm by mass of an aromatic hydrocarbon.
For suppressing the degradation of sensitivity, Japanese Patent Laid-Open No. 2004-4159 discloses an electrophotographic photosensitive member including a photosensitive layer containing a saturated alicyclic ketone with a content in the range of 3000 ppm to 50000 ppm relative to the solid content.
For suppressing fluctuations in potential, Japanese Patent Laid-Open No. 7-5703 discloses an electrophotographic photosensitive member including a photoconductive layer (photosensitive layer) containing 0.05% by weight to 10.0% by weight of cyclopentanone.
The applications of electrophotographic apparatuses are expanding. Some of the electrophotographic apparatuses come to be used for quick printing without being limited to use in offices. Accordingly, an electrophotographic photosensitive member suitable for highspeed processes is desired.
When the electrophotographic photosensitive member disclosed in Japanese Patent Laid-Open No. 2013-142705 was used in a high-speed process with substantially the same amount of light for image exposure as in a general process, however, the electrophotographic photosensitive member exhibited poor sensitivity, and a desired light portion potential was not obtained.
The electrophotographic photosensitive members disclosed in Japanese Patent Laid-Open Nos. 2004-4159 and 7-5703 also exhibited the same disadvantage in some cases.
For coating liquids for forming the layers of an electrophotographic photosensitive member, it is desirable that the solute be fully dissolved in the coating liquid, and that the coating liquid do not deteriorate during storage and have good coatability.
Japanese Patent Laid-Open No. 2001-343762 discloses a coating liquid for forming a charge transport layer (hereinafter referred to as charge transport layer forming coating liquid). In this coating liquid, a solvent made up of dimethoxymethane, ethylene glycol dimethyl ether, and an aromatic hydrocarbon (other than benzene) is used from the viewpoint of preventing the coating liquid from whitening.
Japanese Patent Laid-Open No. 2014-160238 discloses a charge transport layer forming coating liquid from the viewpoint of achieving both a high potential stability and a high abrasion resistance when the photosensitive member is repeatedly used. The coating liquid contains an aromatic hydrocarbon solvent and a compound having a higher boiling point than the aromatic hydrocarbon solvent at 1 atmosphere. Japanese Patent Laid-Open No. 6-308744 discloses a charge transport layer forming coating liquid containing a cyclic ketone as the solvent.
For the technique of Japanese Patent Laid-Open No. 2001-343762, it has been found that the charge transport layer forming coating liquid may gel when stored for a long time. It has also been found that the charge transport layer forming coating liquids disclosed in Japanese Patent Laid-Open Nos. 2014-160238 and 6-308744 may gel when stored under severer conditions for a long time.